The present invention relates to a seal structure for an electronic control apparatus applicable to an engine control unit, an automatic-transmission control unit and the like.
U.S. Patent Application Publication No. 2009/0068862 corresponding to the family Japanese Patent Application Publication No. 2009-70855 discloses a previously proposed seal structure. A seal structure for connector portion of an electronic control apparatus in this technique is close to a structure as shown in FIG. 10B. The electronic control apparatus as FIG. 10B is a so-called connector-side-exposed type in which a part of a connector 2 attached to one side of a circuit board 1 is exposed in a lateral direction of a housing 3 (i.e., in parallel with the circuit board 1) through a window portion of the housing 3. The connector 2 is sandwiched between a pair of members 3a and 3b of the housing 3 in a thickness direction of the circuit board 1. A connector seal portion 4 is provided by charging sealant into a surface-joint portion (surface-contact portion) between an outer circumferential surface of the connector 2 and inner surfaces of the pair of members 3a and 3b of the housing 3 entirely around the connector 2.
In order to secure a predetermined sealing length (also called “leak path”), the connector seal portion 4 is constituted by a seal groove (a connector-side concave portion 2a or a housing-side concave portion 3ba) and a protrusion (a housing-side convex portion 3ab or a connector-side convex portion 2b). A U-shaped clearance between the seal groove and the protrusion is filled with sealant. A reference sign 5 denotes a terminal provided in the connector 2 and connected with a wiring pattern of the circuit board 1.